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The False Economy of Undersized AC Units

14 July 2014

COOLNOMIX Cool News - The False Economy of Undersized AC Units

We commonly hear of the practice of deploying under-sized air-conditioners from numerous partners around the world, particularly in places where the cost of electricity is high. This is an utterly false economy and we think you will be interested in this demonstration of that.

We have assumed two small air-conditioners in the same office in Philippines for the purposes of demonstrating the false economy: one 2 hp and one 2.5hp Midea machines. In Philippines, the first machine to buy costs about US$970 whilst the second machine costs about US$1,150 – an extra capital cost of US$180.

In the calculations below we have assumed a price of electricity in Philippines of US$0.20 per kWh with the air-conditioners running 12 hours per day, 5 days per week, all year-round. The 2hp compressor runs 100% of the time because there is no excess cold supply capacity over the heat load demand whilst we have assumed the 2.5hp compressor runs 70% of the time because it is properly sized for the office in which it is deployed. With these assumptions, the annual running costs for each machine are as follows:

Annual Costs of 2hp AC (US$)

Annual Costs of 2.5hp AC (US$)




You will note the extra annual cost of running the under-sized AC system is US$160 which nearly obliterates any capital cost saving within the first year!

The picture gets worse when we introduce COOLNOMIX®. There is no excess cold supply capacity in the 2hp unit and so even if we deploy COOLNOMIX® no energy savings can be achieved – the annual cost of running the 2hp machine remains at US$975. But since there is some excess capacity on the 2.5hp machine, COOLNOMIX® can deliver some savings on the US$815 annual costs. Assuming the same operating conditions as above, and assuming COOLNOMIX® delivers only 30% savings (not our average achieved 40% savings) then the annual cost savings on the 2.5hp machine from COOLNOMIX® is US$244.

Now compare the annual running costs of the two machines:

Annual Costs of 2hp AC (US$)

Annual Costs of 2.5hp AC with COOLNOMIX® (US$)





Deploying under-sized AC units is a massively false economy! If you really want to burn dollars, deploy under-sized AC’s.

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Alternatively learn more about COOLNOMIX® Optimized Refrigerant Supply by clicking here.

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